This engine comes with a plastic filter clunk and neoprene line. The neoprene line they supplied along with the weight of the plastic cluck caused a similar problem for me. The clunk would not drop and slide inside the tank resulting in deadsticks.
I removed the supplied neoprene line and plastic clunk and replaced with Tygon line and a brass sintered clunk. The sintered clunk is much heavier than the plastic filtered clunk yet still helps prevent sir bubbles in the line and the Tygon line is (for now) more flexible than the supplied neoprene. I have my tank set-up with two clunks, fuel dot , carb feed with outboard filter and the pressure line.
Using the supplied neoprene line on the exhaust to the tank is recommended due to the heat.
Also try and keep the ignition & ignition battery in one place away from the reciever and keep the wires away from other servo wires and metal control rods. If you have to mount the ignition battery away from the ignition keep the wire away from other wires and metal rods.
Once you have the engine broke-in(many,many tanks) you can start to tune the low and high speed settings on the carb and get it running real nice.